Adam Kustka conducting on-deck iron incubation experiments in the Ross Sea, Antarctica. Southern Ocean phytoplankton utilize this “phytotransferrin”, and their growth promotes the removal of carbon dioxide. Lower growth due to ocean acidification could mean even lower rates of CO2 removal, leading to more ocean acidification and lower growth. Credit: Chris Linder

New research out of Rutgers University-Newark, University of California San Diego, and the J. Craig Venter Institute shows that increased CO2 in oceans interfere with necessary iron intake in phytoplankton, which support ocean food chains and fisheries and help moderate CO2 levels.

A team led by scientists from the Scripps Institution of Oceanography at the University of California San Diego, and including Dr. Adam Kustka of Rutgers University-Newark (RU-N), has demonstrated that the excess CO2 society is adding to the atmosphere interferes with a key and previously undescribed pathway for iron uptake in marine phytoplankton.

Phytoplankton are microscopic plants whose growth at the ocean’s surface supports virtually all life in the ocean (including all marine fisheries) and are responsible for removing almost half of the CO2.

Excessive rates of carbon dioxide affect the health of key micro-organisms in the oceans, potentially undermining the base of critical marine food chains, according to new research by US scientists.

A team of researchers from the Scripps Institution of Oceanography and the J. Craig Venter Institute (JCVI) applied techniques from the emerging field of synthetic biology to understand how ocean acidification from the absorption of CO2 is affecting tiny plants known as phytoplankton.

Photosynthetic plankton like these Ross Sea diatoms are key players in the global carbon cycle and form the base of marine food webs, but a new study reveals their ability to acquire iron is highly sensitive to ocean acidification. Credit: Jeff McQuaid

A team led by scientists from Scripps Institution of Oceanography at the University of California San Diego and the J. Craig Venter Institute (JCVI) has demonstrated that the excess carbon dioxide added to the atmosphere through the combustion of fossil fuels interferes with the health of phytoplankton which form the base of marine food webs.

In vast areas of the ocean, the scarcity of iron controls the growth and productivity of phytoplankton. Although most dissolved iron in the marine environment is complexed with organic molecules, picomolar amounts of labile inorganic iron species (labile iron) are maintained within the euphotic zone and serve as an important source of iron for eukaryotic phytoplankton and particularly for diatoms. Genome-enabled studies of labile iron utilization by diatoms have previously revealed novel iron-responsive transcripts, including the ferric iron-concentrating protein ISIP2A8, but the mechanism behind the acquisition of picomolar labile iron remains unknown. Here we show that ISIP2A is a phytotransferrin that independently and convergently evolved carbonate ion-coordinated ferric iron binding. Deletion of ISIP2A disrupts high-affinity iron uptake in the diatom Phaeodactylum tricornutum, and uptake is restored by complementation with human transferrin. ISIP2A is internalized by endocytosis, and manipulation of the seawater carbonic acid system reveals a second-order dependence on the concentrations of labile iron and carbonate ions. In P. tricornutum, the synergistic interaction of labile iron and carbonate ions occurs at environmentally relevant concentrations, revealing that carbonate availability co-limits iron uptake. Phytotransferrin sequences have a broad taxonomic distribution and are abundant in marine environmental genomic datasets, suggesting that acidification-driven declines in the concentration of seawater carbonate ions will have a negative effect on this globally important eukaryotic iron acquisition mechanism.

Researchers study a patch of Australia’s Great Barrier Reef. Scientists say unless the world starts controlling its carbon dioxide emissions, coral reefs will see severely stunted growth by the end of the century. (California Academy of Science/Aaron Takeo Ninokawa)

Researchers fast-forwarded ocean acidification in the Great Barrier Reef to study its impact on corals.

They found that the growth of corals was slowed due to a lack of minerals.

Unless the world starts controlling its carbon dioxide emissions, coral reefs will see severely stunted growth by the end of the century, according to a recent study.

Washington, DC— Ocean acidification will severely impair coral reef growth before the end of the century if carbon dioxide emissions continue unchecked, according to new research on Australia’s Great Barrier Reef led by Carnegie’s Ken Caldeira and the California Academy of Sciences’ Rebecca Albright.

Their work, published in Nature, represents the first ocean acidification experiment in which seawater was made artificially acidic by the addition of carbon dioxide and then allowed to flow across a natural coral reef community. The acidity of the seawater was increased to reflect end-of-century projections if carbon dioxide from greenhouse gas emissions are not abated